EP0477074A1 - Telescopic articulated transmission joint and method of making an element with sliding tracks, especially for such a joint - Google Patents

Abstract

The joint comprises a tripod (1) provided with three spherical journals (41, 42, 43) and a barrel (6) with six internal cylindrical tracks (7). Intermediate elements (10) possess a cylindrical surface (11) complementing the spherical journal (41) and a surface (12) of circular profile complementing the circular profile of the tracks (7). The intermediate elements are blocks whose circular-profiled surface (12) is a cylindrical surface pressed permanently and slidably into the tracks (7). The tracks (7) are defined by linings (19) made of polished glazed steel strip held in place by its own elasticity on pre-tracks (18) of a body (13) of the barrel (6), or bonded to the barrel body during casting of the latter. For use in reducing contact pressures, increasing the telescopic stroke, simplifying the shape of the intermediate elements, enabling them to be made from a material of moderate hardness, and making the manufacture of the barrel particularly economical. <IMAGE>

Description

The present invention relates to a telescopic articulated transmission joint comprising an element with sliding tracks, in particular for the automobile.

The present invention also relates to methods for producing such an element with sliding tracks.

FR-A- 2 607 883 discloses a constant velocity transmission joint comprising a tripod, provided with three arms arranged substantially radially with respect to its axis and partially each surrounded by two roller segments whose radially outer faces, of curved transverse profile, are in rolling contact with longitudinal tracks formed on the inside of a hollow element, of generally cylindrical shape, or "barrel" surrounding the tripod.

FR-A- 2 607 883 and 2 622 653 further teach, by way of improvement, to extend the toroidal rolling surface of the roller segments, at each of its circumferential ends, by a tangent cylindrical surface having the same transverse profile as the toric surface. At the end of rotation, this cylindrical surface comes to bear and slide on the raceway which it marries. This increases the useful stroke of extension and contraction of the joint.

These known seals have remarkable mechanical qualities. The non-slip bearing in the longitudinal tracks of the barrel eliminates friction, while the journaling / oscillation combination between spherical bearings of the roller segments and the tripod arms constitutes a movement without stopping point very favorable for hydrodynamic lubrication and self-polishing of surfaces.

However, the running surfaces, that is to say the outer toric surface of each segment and the corresponding longitudinal track of the barrel are in Hertz contact, that is to say a contact theoretically the along a line and practically along a small area adjacent to this line, under very high pressure due to the load to be transmitted. This requires that these surfaces be very hard to a certain depth. The tracks can for example be subjected to a surface pressure or Hertz pressure, of the order of 200 to 400 Kg / mm², accompanied by a concomitant repeated shear stress reaching approximately 100 Kg / mm² at 1 mm in depth.

Furthermore, French patent application 89 15 105 filed on November 17, 1989 describes a telescopic articulated transmission joint which differs from the joint according to FR-A-2 607 883 in that the toric surface of the pads is replaced by a cylindrical surface. which is permanently supported and sliding on the longitudinal tracks of one of the elements of the joint.

Thus, the bearing pressure of the skates on the tracks is considerably reduced, since it is usually only 0.5 to 2 Kg / mm².

With such pressure values, it is possible a priori to consider considerably reducing the manufacturing cost of the element with longitudinal tracks by using materials which are easy to use, such as mild steel stamped in the sheet or even extruded from of a cylindrical profile and untreated after extrusion. We can also consider the cast iron elements based on iron or aluminum or molded in reinforced plastic or not, or the use of composite materials etc ...

However, there remains the problem that the tracks of the element with longitudinal tracks must have an excellent geometry and above all a surface finish of the polished or “glazed” type in order to allow, as soon as the joint is put into service, that is to say say before any running-in, the hydrodynamic lubrication essential for the sliding without restraint of the pads on the surface of the tracks, these pads having on their side polished spherical and cylindrical surfaces which are relatively adaptable as a result of the constituent material and of the production method chosen, for example molded nylon.

However, the "glossy" surface condition of the pads is free by their method of manufacture and the material used, but on the other hand the grinding and polishing of the tracks, taking into account their length and poor accessibility, prove to be expensive. . One could think of making the element with tracks also made of plastic, but the sliding of plastic onto plastic would be disadvantageous, in particular due to the poor thermal conductivity and the poor heat resistance of the plastic.

The object of the present invention is thus to propose a transmission joint in which the problem of machining the tracks is eliminated, as well as various methods for producing under particularly economical conditions an element with sliding tracks which may be suitable for such a joint. . The processes must allow seals fitted with the elements thus obtained to take full advantage of their high intrinsic comfort performance.

According to a first aspect of the invention, the telescopic articulated transmission joint, in particular for the automobile, comprising a first element and a second element connected to each other in a telescopic articulated manner by intermediate elements which are connected with the first element by ball-type connections having centers distributed around an axis of the first element, each intermediate element further having a surface of substantially circular cross section which comprises a cylindrical surface and which is supported on a respective longitudinal track substantially cylindrical of complementary profile belonging to the second element, the longitudinal tracks having axes distributed around an axis of the second element is characterized in that each intermediate element is a shoe whose cylindrical surface is permanently and slidingly supported on the corresponding cylindrical track of the second element, and in that the cylindrical tracks of the second element are defined by a covering of polished elastic strip plated on the runways of a body of the second element.

According to a second aspect of the invention, the method for producing an element having circumferentially distributed axial sliding tracks, in particular for telescopic articulated transmission joints, in which one starts from a body having fore tracks having a transverse profile conforms to that of the sliding tracks to be produced, is characterized in that it is constrained by elastic bending and there is, opposite the front tracks, a covering of polished elastic strip having, at rest, before mounting, a transverse profile close to that of regions of the body comprising the runways and, the covering is fixed to the body, leaving the covering to undergo partial elastic relaxation until it rests elastically on the avant-tracks so that an outer face polished covering constitutes the tracks.

According to a third aspect of the invention, the method for producing an element having circumferentially distributed axial sliding tracks, in particular for a telescopic articulated transmission joint, in which a body is provided having front tracks having a transverse profile conforming to that of the sliding tracks to be produced is characterized in that the body is produced by molding, and in that, before the filling operation of the mold, is constrained by circumferential elastic bending and there is facing the corresponding mold surfaces at the front slopes, a polished elastic strip covering having at rest, before assembly, a transverse profile close to that of regions of the body including the runways, and the covering is fixed to said mold surfaces by leaving the covering to undergo partial elastic expansion until it rests elastically on these surfaces, then the mold is filled with the material intended to constitute the body and the material is allowed to take hold at least partially and a concomitant adhesion with the covering, so that after demoulding of the body provided with the covering, a polished external face of the covering constitutes the tracks.

Thus, the body of the track element can be made of any of the economic materials mentioned above.

The thin strip, for example 0.1 to 1 mm depending on the materials used, covers the surface defects of the front tracks of the body of the element and provides an optical surface condition conducive to the essential hydrodynamic lubrication.

Given its thinness, the covering is flexible enough to allow very rapid assembly on the track element or respectively on the mold surfaces, by elastic constraint of the covering then release and partial relaxation of the latter against the corresponding wall of the track element body or the mold surfaces.

Given the low surface pressure exerted by the pads of the seal on the tracks defined by the covering during the use of the seal, the covering does not risk any deterioration due to static stresses or fatigue, despite its very small thickness, since 'it does not undergo concentrated pressure or Hertz pressure unlike the active surfaces of constant velocity joints known for example from FR-A-2 607 883.

For the same reason, the strip covering also does not undergo bending stress, even if the material of the barrel on which the covering rests has a modulus of elasticity 10 or 100 times smaller than that of the covering, which is the case for example for a covering of steel strip fitted to a molded nylon barrel.

Preferably, the covering is made from strip finished by cold rolling ("skin pass", literally "skin forming pass") and has a perfectly glazed surface and a constant thickness for a low cost.

• hautes performances de confort grâce à un très libre coulissement ;
• faible coût grâce à un élément à pistes longitudinales dont la fabrication en série est facile et rapide avec des investissements modérés.

The seal according to the invention simultaneously has the following advantages:

• high comfort performance thanks to very free sliding;
• low cost thanks to an element with longitudinal tracks whose mass production is easy and fast with moderate investments.

Other features and advantages of the invention will emerge from the description below, relating to nonlimiting examples.

• la figure 1 est une vue en bout schématique, partiellement en coupe transversale, d'un joint selon l'invention, l'arbre du tripode n'étant pas monté, la moitié inférieure de la figure montrant le barillet seul avec une fourrure ;
• la figure 2 est une vue en coupe selon le plan II-II de la figure 1, l'arbre du tripode étant monté ;
• la figure 3 est une vue schématique en coupe selon la ligne III-III de la figure 1, la partie droite n'étant que partiellement représentée ;
• la figure 4 est une vue en plan d'un patin, côté portée cylindrique ;
• la figure 5 est une vue en plan d'un patin, côté portée sphérique ;
• la figure 6 est une vue analogue à la figure 2, lorsque le joint fonctionne sous un angle de brisure ;
• la figure 7 est une vue de face du barillet, dont la bride n'est pas représentée ;
• la figure 8 est une vue en perspective d'une fourrure ;
• la figure 9 est une vue en coupe axiale du barillet muni de deux modes de réalisation des fourrures ;
• la figure 10 est une vue en perspective du deuxième mode de réalisation des fourrures ;
• la figure 11 est une vue en perspective d'un troisième mode de réalisation des fourrures ;
• la figure 12 est une vue en bout d'un quatrième mode de réalisation des fourrures ;
• la figure 13 est une vue en bout d'un barillet équipé du quatrième mode de réalisation des fourrures, la bride du barillet n'étant pas représentée ;
• la figure 14 est une vue en élévation latérale d'une ébauche en vue de la fabrication du quatrième mode de réalisation des fourrures ;
• la figure 15 est une vue en bout, avec coupe partielle, d'un deuxième mode de réalisation du joint ;
• la figure 16 est une vue en coupe axiale du barillet de ce joint ;
• la figure 17 est une vue de face du corps de ce barillet, sa bride n'étant pas représentée ;
• la figure 18 est une vue en élévation latérale d'une ébauche au cours de la fabrication de la fourrure du joint de la figure 15 ;
• la figure 19 représente en perspective à l'état libre un exemple de fourrure en feuillard mince pour la mise en oeuvre d'un autre procédé selon l'invention ;
• la figure 20 représente schématiquement en coupe axiale un moule muni des fourrures avant injection du matériau, la partie supérieure de la figure correspondant à un barillet portant une fusée, et la partie inférieure de la même figure correspondant à un barillet à bride ;
• la figure 21 est une coupe transversale selon la ligne XXI-XXI de la figure 20 ;
• la figure 22 représente à l'état libre une fourrure prête au montage sur le noyau du moule d'un barillet destiné à un joint sensiblement selon la figure 15 ;
• la figure 23 est une coupe schématique d'un moule pour le barillet comportant la fourrure de la figure 22, laquelle est encliquetée sur noyau ;
• la figure 24 représente la fourrure de la figure 22 après un premier stade de pliage ; et
• la figure 25 est une coupe longitudinale du barillet obtenu par le procédé des figures 22 à 24, la partie supérieure illustrant le cas où le barillet est surmoulé sur une fusée à épanouissement denté, tandis que la partie inférieure illustre celui où le barillet est fixé au plateau de fusée par dentures frontales et écrou.

In the accompanying drawings:

• Figure 1 is a schematic end view, partially in cross section, of a seal according to the invention, the tripod shaft not being mounted, the lower half of the figure showing the barrel alone with a fur;
• Figure 2 is a sectional view along the plane II-II of Figure 1, the tripod shaft being mounted;
• Figure 3 is a schematic sectional view along line III-III of Figure 1, the right part being only partially shown;
• Figure 4 is a plan view of a shoe, cylindrical bearing side;
• Figure 5 is a plan view of a pad, spherical bearing side;
• Figure 6 is a view similar to Figure 2, when the seal operates at a breaking angle;
• Figure 7 is a front view of the barrel, the flange is not shown;
• Figure 8 is a perspective view of a fur;
• Figure 9 is an axial sectional view of the barrel provided with two embodiments of the furs;
• Figure 10 is a perspective view of the second embodiment of the furs;
• Figure 11 is a perspective view of a third embodiment of the furs;
• Figure 12 is an end view of a fourth embodiment of the furs;
• Figure 13 is an end view of a barrel equipped with the fourth embodiment of the furs, the barrel flange not being shown;
• Figure 14 is a side elevational view of a blank for the manufacture of the fourth embodiment of the furs;
• Figure 15 is an end view, partly in section, of a second embodiment of the seal;
• Figure 16 is an axial sectional view of the barrel of this seal;
• Figure 17 is a front view of the body of this barrel, its flange not being shown;
• Figure 18 is a side elevational view of a blank during the manufacture of the seal fur of Figure 15;
• Figure 19 shows in perspective in the free state an example of thin striped fur for the implementation of another method according to the invention;
• FIG. 20 schematically represents in axial section a mold provided with the furs before injection of the material, the upper part of the figure corresponding to a barrel carrying a rocket, and the lower part of the same figure corresponding to a barrel with flange;
• Figure 21 is a cross section along the line XXI-XXI of Figure 20;
• Figure 22 shows in the free state a fur ready for mounting on the core of the mold of a barrel intended for a seal substantially according to Figure 15;
• Figure 23 is a schematic section of a mold for the barrel comprising the fur of Figure 22, which is snapped onto the core;
• Figure 24 shows the fur of Figure 22 after a first stage of folding; and
• FIG. 25 is a longitudinal section of the barrel obtained by the method of FIGS. 22 to 24, the upper part illustrating the case where the barrel is overmolded on a flare with toothed development, while the lower part illustrates that where the barrel is fixed to the rocket plate by front teeth and nut.

In the example shown in Figures 1 to 6, the transmission joint of the constant velocity type, serves to connect in an articulated and telescopic manner and to ensure the transmission of a torque between a shaft 9 which can be connected to a power source of the vehicle and a shaft 2 which may be the joint output shaft towards the drive wheel of a motor vehicle. The seal comprises a first element constituted by a tripod 1 in turn comprising a ring 1a which is fitted on the shaft 2 and which is made integral with the shaft 2 in rotation about the common axis ON of the ring and the shaft 2 by means of conventional grooves or by any other appropriate means.

The tripod further comprises three spherical journals 41, 42, 43 integral with the ring la and extending radially outward therefrom. The centers T₁, T₂ and T₃ of the trunnions are distributed regularly around the axis ON and are located all three in the same plane cutting the axis ON perpendicularly at a point 0. In addition, the centers T₁, T₂ and T₃ are equidistant from the ON axis.

The spherical journals 41, 42, 43 each have two convex spherical bearing regions 4a, which belong to the same ideal sphere of center T₁, T₂ and T₃ respectively, depending on the journal considered. The two spherical bearing regions 4a of each pin 4 belong to the same ideal sphere and are separated from each other by two flats 5, so as to limit the dimension of the tripod parallel to the axis ON.

The seal further comprises a second element constituted by a barrel 6, of generally cylindrical shape, which internally carries six longitudinal tracks 7 having a substantially circular concave transverse profile. The pin 41 extends between the tracks 7 of axis P₁₁ and P₁₂ and each of its spherical bearing regions 4a is turned towards a respective one of these two tracks. The same applies to the journal 42 with respect to the tracks of axis P₂₁ and P₂₂, and the journal 43 with respect to the tracks P₃₁ and P₃₂.

The barrel 6 comprises at an end opposite the shaft 2 a fixing flange 6a by which it is fixed to a plate 8 by means of screws which are only represented by their axes 8a. The plate 8 is integral with the shaft 9 of the power take-off of the vehicle. The axes of the tracks 7 are parallel to the axis Z of the shaft 9 and located at an equal distance from the latter.

The axes P₁₁ and P₁₂ of the two tracks located on either side of the journal 41 are arranged symmetrically on either side of a half-plane ZZ₁ (Figure 1) from the Z axis and passing through the center T₁. When the joint is aligned, (axes ON and Z combined), the center of the pin T₁ is located at a very small radial distance beyond a plane PP₁ to which the two axes P₁₁ and P₁₂ of the two tracks 7 located share and other of the journal.

Of course, the other two journals and the tracks associated with them obey strictly corresponding rules.

The articulated and telescopic connection between the barrel 6 and the tripod 1 is effected by six pads 10 each of which is interposed between one of the tracks 7 and the spherical support region 4a located opposite. Each shoe 10 has a concave spherical surface 11 of the same radius as the spherical bearing regions 4a and which is in sliding contact with the corresponding spherical bearing region 4a of the tripod. Thus, in the assembled state, the center U of the concave spherical surface 11 (FIG. 5) of each shoe 10 coincides with the center T₁, T₂, or T₃ of the corresponding pin (Figures 1 to 3 and 6).

Each shoe 10 further comprises a convex cylindrical surface with circular section 12, of axis QQ ′ (FIGS. 4 and 5) and of radius equal to the radius of the circular profile of the tracks 7. In service, the convex cylindrical surfaces 12 are in contact with the concave tracks 7, the axes QQ ′ (FIG. 4) of the surfaces 12 respectively coinciding with the axes P₁₁, P₁₂ etc ... of the tracks 7 of the barrel 6.

The pads 10 are capable of sliding along the tracks 7 and of oscillating around the aforementioned axes in the tracks 7 by their sliding contact with the latter. Furthermore, the pads 10 are capable of journalling and oscillating on the pins 41, 42 and 43 thanks to the sliding contact between the concave spherical surfaces 11 of the pads 10 and the spherical bearing regions 4a of the pins.

According to the invention, the barrel 6 comprises a body 13 (see also FIG. 7) of generally cylindrical shape, an inner peripheral wall of which comprises three longitudinal ridges 14 regularly distributed around the axis Z and which define between them cells 16 which have an undercut shape in the sense that their maximum dimension B ′ measured in a tangential direction relative to the axis Z, is greater than the tangential dimension B˝ of their opening towards the axis Z.

Each cell 16 is defined by two pre-tracks 18 each backed by one of the ridges 14, and connected to each other by a cylindrical connecting face 17, of axis Z and of radius R. tracks 18 have the same axis P₁₁, P₁₂, P₂₁, P₂₂, P₃₁, P₃₂ as tracks 7 to be produced but have a slightly increased radius compared to these.

The barrel 6 further comprises on the inner peripheral wall of the body 13, a covering constituted in the example of three individual furs 19 (FIGS. 1 and 8) which each cover the surface of the cell 16, that is to say say the two front tracks 18 and the connecting face 17. The covering therefore also extends outside the tracks 7, over almost the entire inner contour of the barrel, which allows it in service, thanks to its thermal conductivity, to distribute and dissipate in particular throughout the barrel and the lubricant the heat generated by the sliding under load. This characteristic allows despite the thinness of the strip the transmission of a large power at an angle without risk of prohibitive heating for the plastic material constituting the barrel body and the pads.

Each fur 19 is made of strip finished by cold rolling so as to present on its concave face turned away from the body 13 a perfectly glazed surface. This strip, cut to length desired from a continuous strip, is then bent so as to define on its concave face the two tracks 7 substantially with the desired radius corresponding to the radius of the cylindrical surfaces 12 of the pads 10. The two tracks 7 are connected by a vault link 21 whose convex outer face has at rest, before mounting, a radius R ′ slightly greater than the radius R of the connecting faces 17 of the body 13.

Before bending, the circumferential edges of each fur 19 are cut so as to provide tabs 22 at the ends of the tracks 7 which are folded out at right angles to the outside.

To mount the furs 19 in the body 13, as shown in FIG. 7 at the bottom right, the fur 19 is presented opposite the corresponding cell 16, and it is placed under circumferential bending stress, illustrated by arrow 23 , then it is pushed radially outwards into the cell 16 as illustrated by the arrow 24, so as to make it cross the narrow entrance (of width B˝), then it is left to partially relax in the cell 16. The relaxation cannot be total since the radius at rest R ′ of the arch 21 is greater than the internal radius R of the connecting face 17 of the cell 16. Under these conditions, the fur 19 remains under stress and therefore pressed against the front tracks 18 and the connecting face 17 of the cell.

The distance between the tongues 22 of the two ends of the fur 19 corresponds to the distance between two faces 26 and 27 (FIG. 9) of the body 13 into which the avant-pistes 18 open. When the furs 19 are in place in the body 13 , the tongues 22 bear on the faces 26 and 27 and thus position the furs 19 axially relative to the body 13.

In the embodiment shown at the bottom of FIG. 1, quine will be described only as regards its differences from the previous one, each fur 29 defines two tracks 7 backed by the same crest 14 and consequently belonging to two different cells 16. The two tracks 7 are joined to each other by a connecting region 31 which has a hairpin profile surrounding the enlarged free end of the ridge 14.

As shown at the bottom of FIG. 1, in order to put a fur 29 on the body 13, the connecting region 31 is elastically constrained in circumferential bending so as to increase its radius of curvature to make it cross the widened end of the ridge 14, according to the arrows 33, then it is pushed radially outwards according to arrow 34, leaving it to undergo a partial elastic relaxation which presses against the fore-tracks 18 the regions of the fur 29 which define the tracks 7.

The embodiment of FIG. 11 is identical to that of FIG. 8 and from the top of FIGS. 1 and 9, except that the fur 19 is stripped of tongues 22 but, on the other hand, has two openings 32, preferably rectangular, through its vault 21 or circular in which fit bosses 36 (shown in phantom in Figure 7) provided on the connecting face 17 of the cells 16. The interpenetration of openings 32 and bosses 36 axially positions the furs 19 in the body 13 This embodiment avoids having to cut the edges of the strip from which the furs are made, and thus the corresponding falls are avoided.

In the example shown in Figures 12 and 13, quine will be described that with regard to its differences from that at the top of Figures 1 and 9, the entire covering is made by means of a single fur 39 defining the six tracks 7 joined together two by two by three connecting regions 31 similar to the connecting region 31 of the fur 29 at the bottom of FIG. 1. The fur 39 is interrupted by an axial slot 38 which has at rest, before mounting, a relatively large dimension, but which is reduced to a simple gap (FIG. 13) when the fur 39 is installed inside the body 13.

The two tracks 7 adjacent to the slot 38 are each connected to a terminal half-arch 37. The other four tracks 7 are two by two connected by arches 21. As shown in FIG. 12, the arches 21 have a radius at rest outside R ′ greater than the inside radius R of the connecting faces 17 of the body 13.

To set up the fur 39, it is wound on itself by overlapping the two edges intended to define the slot 38, and it is threaded axially in the body 13. This winding has the effect of both d 'deviate from the connecting regions 31, that is to say to increase their radius of curvature, and on the contrary to reduce the radius of curvature of the vaults 21. We thus manage to engage the ridges 14 in the regions 31 and at the same time the arches 21 in the cells 16. The fur 39 is then partially allowed to relax in the body 13 so that the regions defining the tracks 7 are pressed against the front tracks 18.

As shown in FIG. 14, to make the furs 39, it is advantageously possible to start from a continuous strip of strip, the longitudinal dimension of the strip being intended to correspond to the circumferential dimension of the fur to be manufactured. The tongues 22 are first formed then the tracks 7 and the connecting regions 31, in a single bending operation for each pair of tracks 7 connected by a region 31. It is also at this stage that the tongues are folded 22 square. Then the fur blank 39 ′ is sliced from the rest 39 "of the strip, as shown by the dashed line 44, then the intermediate parts 21 ′ are curved to form the arches 21 of radius R. The regions 37 ′ intended to form half-arches 37 are also curved, to have a radius of curvature slightly greater than R, but possibly less than R ′.

The circumferential dimension of the slot 38 (FIG. 12) of the fur at rest before mounting is chosen according to the own elasticity and the thickness of the material used for the fur, as well as according to the elastic force desired for maintaining the fur in the body 13 of the barrel.

The transmission joint according to FIG. 15 will only be described with regard to its differences from that of FIG. 1.

The longitudinal tracks 47 of the barrel 6 are convex cylindrical tracks having a cross section in a segment of a circle whose axes M₁₂, M₂₃ and M situés are located beyond the active surfaces of these tracks relative to the center T₁, T₂ or T₃ of the pin 41 , 42 or 43 associated.

Each axis M₁₂, M₂₃ or M₃₁ is common to two adjacent tracks 47 cooperating with two different pins. Each pair of tracks 47 having a common axis M₁₂ or M₂₃ or M₃₁ is formed by two longitudinal regions, extending side by side, of the same convex cylindrical surface facing the axis Z of the barrel. Thus, the cylindrical active surface of axis M₁₂ receives both one of the pads 50 supported on the pin 41 and one of the pads 50 supported on the pin 42.

The cylindrical surface of each shoe 50 is a concave cylindrical surface 52 of the same axis and same radius as the tracks 47, and which slides longitudinally and transversely on the track 47 which is associated with it.

The body 13 of the barrel 6 comprises on its inner peripheral face convex cylindrical fore-tracks 58 of axis M₁₂, M₂₃, M₃₁ and of radius slightly less than that of the tracks 47. The three fore-tracks 58 are connected by faces of 57 cylindrical link concave of axis Z. The barrel 6 is closed at one of its ends by a wall 48 of the body 13, which is fixed by screws 46 to an end flange 49 of the shaft 9. Mutual centering 49a of the flange 49 and of the wall 48 ensures coaxiality between the shaft 9 and the barrel 6. The head of the screws 46 is partly received in recesses 64 formed in the external wall of the body 13 on the back of the front tracks 58. The screws 46 pass through the holes 51 of the flange 6a of the body 13 to be screwed into threaded holes of the flange 49. The axis 46a of the screws 46 is shown parallel to the axis Z of the barrel, but, as a variant, the screws 46 can be mounted along an axis 46b inclined towards the shaft 9 to facilitate screwing.

This fixing of a reduced bulk uses both the possibility of producing the recesses 64 on the back of the lead tracks 58 and the ease with which these recesses can be produced during the molding of the barrel in materials such as metal cast irons or plastics reinforced or not.

This removable, economical, compact and light attachment therefore constitutes an additional advantage arising from the present invention.

In this example, the covering is produced by a single fur 59 which covers the entire interior wall of the body 13 with the exception of the slot 38 which, as in the previous example, has a relatively large value when the fur is at rest before mounting, but is reduced to a simple gap when the fur is in place inside the body 13.

The fur 59 has a profile corresponding to that of the inner wall of the body 13 and thus has convex regions defining the tracks 47 alternating with concave regions defining the volts 21 covering the connecting faces 57. At rest, the arches 21 have a outer radius larger than the inner radius of the connecting faces 57 so that the fur is pressed by elastic stress against the inner wall of the body 13 over its entire periphery.

In the example shown in the upper part of Figures 15 and 16, the fur 59 has on its peripheral edges tabs 22 which respectively apply to the end face 26 of the body 13 and engage in grooves 53 made in the apex of the runways 58 in the vicinity of the wall 48.

In the example shown at the bottom of FIGS. 15 and 16, the tongues 22 are replaced by the openings 32 and bosses 36 already described with reference to FIG. 11 and to FIG. 7 respectively.

FIG. 18 represents the fur 59 at an intermediate stage of its mass production from a continuous strip of strip. The tracks 58 are formed as well as the tongues 22. In the case where openings 32 are provided in place of the tongues 22, these have also already been cut. To successively form the tracks 47, the regions 21 ′ intended to constitute the arches 21 are initially given a curvature in the same direction as the tracks 47, so that the strip still retains at this stage a very generally rectilinear configuration. The strip is then cut to the desired length and it is only then that the curvature of the regions 21 ′ is reversed so that they form the arches 21.

In all the examples which have just been described, the strip from which the furs are produced can be made of steel, of copper or aluminum alloy. It can also be plated with material suitable for sliding, by electrolysis or any other known means. The retaining of the furs can also be supplemented by their partial or total bonding on the barrel. The choice depends on the assembly machines and the constituent material chosen for the barrel.

We will now describe with reference to FIGS. 19 to 21 a second method for producing the barrel 6 of a transmission joint quite similar to that shown in FIGS. 1 to 6.

A mold 71 is used which essentially comprises three parts, namely a housing 72 which will in particular form the annular end face of the barrel body, a core 73 and a cover 77. The core 73 comprises for its centering relative to the housing 72. This axis is an axis 74 received in a central bore in the bottom of the housing 72. This axis is terminated by a thread on which is tightened a nut 76 resting on the bottom of the housing 72 to immobilize the core 73 against the interior wall of the bottom of the housing 72. The cover 77 is intended in particular to form the rear face of the barrel, opposite the axis of the tripod.

In the example shown at the top of FIG. 20, it is essentially the cover which forms the external lateral wall of the barrel. On the contrary, in the example shown at the bottom of FIG. 20, it is the housing 72 which performs this function, since the plane of joint between the housing 72 and the cover 77, corresponding substantially to the plane XXI-XXI, is close of a region 78 of the interior space of the mold in which a fixing flange for the barrel to be produced must form. Individual cores 79 engaged in the housing 72 and in the cover 77 are provided to form holes 81 (FIG. 1) in the flange 6a to be produced.

In the example shown in the upper part of Figure 21, the barrel will be made without flange. On the other hand, the cover 77 comprises a central bore 82 in which is positioned a cylindrical surface 83 of the rocket 9 to which the barrel must in service be rigidly connected. The rocket 9 is pressed axially against a shoulder 84 of the core 73 and is fitted centrally on a cylindrical boss 86 of the core 73. In In this situation, a toothed bloom 87 of the rocket 9 projects radially into the molding space, being axially spaced both from the core 73 and from the cover 77, so that the material comes to trap it axially on either side. development 87 during injection while the development teeth 87 will ensure the circumferential connection between the rocket 9 and the material of the molded body.

Before injecting the material of the body into the mold 71, and even before closing the mold by bringing the press piston 87 to which the cover 77 of the mold is attached, to the table 88 to which the housing 72 is fixed, we begin by placing on each of three lobes 91 of the core 73 an elastic striped fur shown in Figure 19. This fur 89 will only be described with regard to its differences from the fur 19 of Figure 11. Its inner cord E ′ is slightly smaller than the corresponding outer chord E of a lobe 91. The chord E is equal to the desired inner chord between the two tracks 7 of the barrel to be made, except corrections to be made to take account of shrinkage and contraction of the injected material. This feature is obtained by giving the connecting vault 21 an initial internal radius R ′ smaller than the corresponding radius R of the lobes 91. On the other hand, the radius r of the tracks 7 has from the outset its desired value for the completed transmission joint . Furthermore, the concave face of the furs 89, which is that intended to constitute in particular the tracks 7, has a polished "glossy" surface state, whereas on the contrary, the other face is preferably frosted, not only for reasons of economy, but also to promote its adhesion with the plastic material of the barrel body.

To place the furs 89 on the core 73, they are elastically deformed to increase the radius of curvature, in particular of the connecting vault 21, as shown at the bottom left of Figure 21 schematically. The spacing shown in FIG. 21 can prove to be excessive in certain cases, in particular if the strip is relatively thick, but it is also possible to thread the furs 89 axially from the end of the core 73 opposite the bottom of the housing 72 This latter mounting method is particularly preferred in the case illustrated at the bottom of FIG. 20 where the housing 72 makes it quite difficult to snap in in the radial direction.

Once the furs 89 are in place, their concave faces intended in particular to constitute the tracks 7 are pressed against corresponding convex surfaces 75 (FIG. 21) of the core 73 while the convex, exposed, preferably frosted, faces of the furs could be coated with an adhesive. These exposed faces of the furs are intended to form the front tracks of the body that we are going to mold and to adhere to them. The mold is then closed by displacement of the piston 87 relative to the table 88, and the plastic material is injected by injection ports, not shown, distributed in the manner that a person skilled in the art knows how to determine.

After the plastic material has taken hold, which invades the space left free inside the mold, in particular the openings 32 of the furs 89, the furs are integral with the plastic material constituting the body of the barrel. For demolding, it suffices to separate the piston 87 from the table 88 and to eject the barrel with which, if necessary (upper half of FIG. 20) the rocket 9 is integral.

The example in FIGS. 22 to 25 illustrates a method for producing the barrel of a seal of the type shown in FIG. 15.

The mold used is similar to that shown in Figures 20 and 21 except that the core central has a different profile (Figure 23), complementary to the free space to be provided inside the barrel.

In this example, the six tracks 47 (FIG. 15) are formed in a single strip of steel strip 99 having “glossy” polished surfaces and of thin thickness (preferably 0.2 to 1 mm).

Figure 24 shows the blank of the strip fur 99 after the first press folding operation. The tracks 47 are arched at their almost final radius as well as the connecting half-arches 92 at the two ends, the two intermediate connecting arches 21 ′ on the other hand have their inverted curvature. The openings of rectangular or circular shape 42 are cut prior to the first forming operation, at the same time as the shearing to length of the strip. The number, the distribution and the shape of the openings 42, always located outside the tracks 47, are given here by way of example.

The second and last forming operation reverses the curvature of the connecting vaults 21 ′ in order to obtain the fur 99 shown in FIG. 22 ready to be fitted onto the core 73 of the mold.

In the free state, the ends 93 of the fur are superposed and the curvatures, in particular of the vaults 21, are altered so that once they are fitted onto the core of the mold by elastic opening, in particular enlargement of the radius of curvature of the vaults 21, the fur 99 presses the profile of the core 73 of the mold on its periphery as shown in FIG. 23.

The barrel obtained after injection of material into the mold, setting of this material and demolding is shown in FIG. 25.

During molding, the openings 32 are filled with injected material which forms in these openings anchoring studs 94 supporting the fixing of the fur 99 inside the body 13 of the barrel. Song 96 of the fur 97 can be flush with the edge of the barrel, as shown in Figure 25, where it is set back 1 or more mm.

The upper part of FIG. 25 represents the barrel 6 obtained when, as shown in FIG. 20, during the core molding in the barrel material, there is a toothed bloom 87 of the rocket 9. In other words, the bloom 87 constitutes a molding insert in the bottom 48 of the barrel 6.

The lower part of FIG. 25 represents a variant of this barrel, in which the bottom 48 carries on its rear face, turned in service opposite the shaft 2 of the tripod, front teeth 97 obtained during molding. The steel rocket 9 provided with an end plate 98 also carries complementary front teeth 101 cold formed and axially locked against the bottom of the barrel by means of a sheet metal nut 102 according to the technique proposed by the FR - A - 1,586,379 and FR - A - 2,426,831.

• pistes parfaitement polies ou "glacées" procurant un glissement lubrifié hydrodynamiquement, assurant le confort et la longévité recherchés ;
• dissipation de la chaleur de glissement dans toute la masse du barillet et du lubrifiant, permettant la transmission sous angle d'une puissance importante ;
• constance de cotes donc, jeux d'assemblage réduits en fabrication de grande série et par conséquent absence de chocs aux inversions de couple et donc confort de conduite ;
• construction légère et insonore ;
• coût réduit de production en grande série, grâce aux cadences de réalisation permises, au faible colt de la matière première et à la modicité des investissements.

The barrels which have just been described and their methods of obtaining, as well as the seals which are equipped with them, have the following advantages:

• perfectly polished or "glazed" tracks providing a hydrodynamically lubricated sliding, ensuring the desired comfort and longevity;
• dissipation of the sliding heat throughout the mass of the barrel and of the lubricant, allowing the transmission under angle of a large power;
• consistency of dimensions therefore, reduced assembly play in mass production and consequently absence of shocks to torque reversals and therefore driving comfort;
• light and soundproof construction;
• reduced cost of mass production, thanks to the production rates allowed, low cost raw material and low investment.

Of course, the invention is not limited to the examples described and shown.

One can for example envisage the application of the invention to transmission joints in which the sliding tracks are carried by the inner element of the joint, or even to transmission joints comprising more or less than three pairs of sliding tracks.

Claims (34)

Articulated telescopic transmission joint, in particular for the automobile, comprising a first element (1) and a second element (6) connected to each other in a telescopic articulated manner by intermediate elements (10, 50) which are connected with the first element (1) by ball-type connections (11, 4a) having centers (T₁, T₂, T₃) distributed around an axis (ON) of the first element, each intermediate element (10, 50) having furthermore, a substantially circular cross-sectional surface which comprises a cylindrical surface (12, 52) and which is supported on a respective substantially cylindrical longitudinal track (7, 47) of complementary profile belonging to the second element (6), the longitudinal tracks having axes (P₁₁, P₁₂, P₂₁, P₂₂, P₃₁, P₃₂, M₁₂, M₂₃, M₃₁) distributed around an axis (Z) of the second element,
characterized in that each intermediate element is a shoe whose cylindrical surface (12, 52) is permanently and slidingly supported on the corresponding cylindrical track (7, 47) of the second element (6), and in that the cylindrical tracks of the second element are defined by a strip covering (19, 29, 39, 49, 59, 89, 99) elastic polished plated on front tracks (18, 58) of a body (13) of the second element (6 ). Joint according to claim 1, characterized in that the covering (19, 29, 39, 49, 59, 89, 99) is extended outside the tracks (7, 47). Joint according to one of claims 1 or 2, characterized in that the covering (39, 59, 89, 99) has, outside the tracks, openings (32) for axial positioning, in which are complementary bosses (36) ) of the body (13). Joint according to one of claims 1 to 3, characterized in that the body (13) comprises cells (16) separated by ridges (14) and each defining two concave pre-tracks (18) and a face (17) connecting between these two pre-tracks, and in that the covering comprises for each cell a fur ( 19, 39, 89) defining the two tracks (7) of a cell and a connecting region (21) between these two tracks. Joint according to one of claims 1 to 3, characterized in that the covering comprises a fur (49, 59, 99) covering substantially the whole of a peripheral wall of the body (13) except for a thin longitudinal slot (38) located off the tracks (7, 47). Joint according to one of claims 1 to 3, characterized in that the substantially cylindrical tracks (47) have the same radius and have two by two the same axis (M₁₂, M₂₃, M₃₁). Transmission joint according to claim 6, in which the second element (6) is a barrel and the tracks (47) are convex tracks carried by an inner face of the barrel, characterized in that each pair of tracks (47) having a common axis (M₁₂, M₂₃, M₃₁) is in contact with two aforementioned intermediate elements (50) supported on substantially spherical bearing regions (4a) belonging to two distinct pins (41, 42, 43) of a tripod (1 ) constituting the first element. Transmission joint according to claim 7, characterized in that the barrel has external recesses (64) at the back of the convex tracks (47) and in that in these recesses (64) are housed at least partially screws (46) fixing the barrel (6) to a flange (49) of the shaft end (9). Transmission joint according to one of claims 1 to 8, characterized in that the pads (10, 50) are made of a material chosen from the group comprising plastics, in particular nylon, porous sintered metals impregnated with lubricant, steel coated with plastic material, in particular nylon, alloys based on copper, lead or tin. Transmission joint according to one of claims 1 to 9, characterized in that the covering (19, 29, 39, 49, 59, 89, 99) is made of a material chosen from the group comprising steel, copper and aluminum alloys, the straps clad with materials suitable for sliding. Transmission joint according to one of claims 1 to 10, characterized in that the body (13) is a molded part. Transmission joint according to claim 11, characterized in that the body is overmolded on a shaft end provided with conformations (87) of axial and circumferential mutual fastening. Transmission joint according to claim 11, characterized in that the body (13) has, at a distance from its axis (Z) on a face opposite the first element, conformations (97) on which complementary conformations (101) of a shaft end can be clamped by a clamping means (102). Joint according to one of claims 1 to 3, characterized in that the body (13) comprises cells (16) separated by ridges (14) and each defining two concave pre-tracks (18) and one face (17) of connection between these two pre-tracks, and in that the covering comprises for each cell a fur (19, 39, 89) defining the two tracks (7) of a cell and a connecting region (21) between these two tracks. Joint according to one of claims 1 to 14, characterized in that the covering (19, 29, 49, 59) comprises, at each end, tongues (22) for axial positioning, supported on faces (26, 27, 53 ) of the body (13) adjacent to the ends of the front tracks (18, 58). Transmission joint according to one of claims 1 to 15, characterized in that the covering (19, 29, 39, 49, 59) is pressed against the front tracks (18, 58) by its own elasticity. Transmission joint according to one of claims 1 to 13, characterized in that the covering is, on at least part of its surface, adhered to the body (13) of the second element (6). Method for producing an element (6) having circumferentially distributed axial sliding tracks (7, 47), in particular for a telescopic articulated transmission joint, in which one starts from a body (13) having front tracks (18, 58) having a transverse profile conforming to that of the sliding tracks to be produced, characterized in that it is constrained by circumferential elastic bending and there is a facing (19, 29, 39, 49, 59) in polished elastic strip having at rest, before mounting, a transverse profile close to that of regions of the body (13) comprising the front tracks (18, 58), and the covering is fixed to the body leaving the 'dressing undergo partial elastic relaxation until it rests elastically on the front tracks (18, 58) so that a polished outer face of the covering constitutes the tracks (7, 47). Method according to claim 18, characterized in that to constrain the covering, the radius of curvature (R ′) is reduced by at least part of the covering (19, 39, 49, 59), and, when partial elastic relaxation, this part is allowed to rest against a concave inner face (17, 57) of the body (13). Method according to one of claims 18 or 19, characterized in that the covering (19, 29, 49, 59) is positioned axially by means of tongues (22) carried by the covering, which are supported on the faces (26, 27) of the body adjacent to the ends of the fore tracks (18). Method according to one of claims 18 or 19, characterized in that the covering (39, 59) is positioned axially by engaging bosses (36) of the body (13) in corresponding recesses (32) formed in the dressing. Method according to claim 18, characterized in that to constrain the covering (29, 49), a region (31) of the covering which has a hairpin profile connecting two tracks (7) is removed, and when partial elastic relaxation is allowed to resiliently close this region (31) so that it pinches a crest (14) on which are backed two pre-tracks (18) of the body (13). Method according to claim 22, characterized in that furs (29) are used as coverings, each covering a longitudinal crest (14) of the body (13) and two pre-tracks (18) attached to this crest. Method for producing an element (6) having circumferentially distributed axial sliding tracks (7, 47), in particular for a telescopic articulated transmission joint, in which a body (13) having pre-tracks (18, 58) is produced having a transverse profile conforming to that of the sliding tracks to be produced, characterized in that the body is produced by molding, and in that, before the filling operation of the mold (71), one constrains by circumferential elastic bending and a covering (89, 99) in polished elastic strip having at rest, before mounting, a transverse profile close to that of the regions of the body is presented facing the surfaces (75) of the mold corresponding to the front tracks (18, 58). 13) comprising the front tracks (18, 58), and the covering is fixed to said mold surfaces, leaving the covering to undergo partial elastic relaxation until it rests elastically on these surfaces (75), then the world is filled with the material intended to constitute the body and it is allowed to operate an at least partial grip of the material and a concomitant adhesion of the latter with the covering, so that after demolding of the body provided with the covering, a polished external face of the covering constitutes the tracks (7, 47) . Method according to claim 23, characterized in that to constrain the covering, the radius of curvature (R ′) is increased by at least part (21) of the covering (89, 99), and, when partial elastic expansion, this part is allowed to rest against a convex face (75) of the mold (71). Method according to one of Claims 24 or 25, characterized in that recesses (32) are formed on the covering, before its mounting on the surfaces (75) of the mold, in which, during molding, the material of the body forms bosses (36) for securing between the body (13) and the covering (89, 99). Method according to one of claims 24 to 26, characterized in that a shaft end provided with axial and circumferential retaining conformations (87) is positioned in the mold (71), and in that the body is overmolded (13) on this end of the tree. Method according to one of claims 24 to 27, characterized in that a strip is used which is frosted on the face opposite to the surfaces (75) of the mold. Method according to one of claims 18 to 21 and 24 to 28, characterized in that furs (19, 39, 89) are used as covering, each covering, on the body, two avant-tracks (18) and a region connecting (17) which together define a cell (16) undercut on a peripheral wall of the body (13). Method according to one of claims 18 to 21 or 24 to 28, characterized in that by means of the covering (49, 59, 99) produced in one piece, substantially all of the body (13) is covered a peripheral wall comprising the runways (18). Method according to claim 30, characterized in that, to make the covering, a strip of continuous strip is started, the tracks (7, 47) are formed by local bending of this continuous strip, it is cut to obtain a section, then the regions (21) of the section located between the tracks (7, 47) are bent in order to bring the two ends (93) of the section closer to one another and thus obtain the covering. Method according to claim 31, characterized in that before cutting the strip, the regions (21 ′) situated between the tracks (47) are bent in a first direction opposite to that of the bending of the same region (21) after that the tape has been cut. Method according to one of claims 18 to 32, characterized in that the covering (19, 29, 39, 49, 59) is given, at rest before mounting, for the tracks (7, 47), a radius of curvature which corresponds to that of the tracks after assembly, and for regions other than the tracks (21, 31), a radius of curvature different from that which said regions will have when the covering is in place on the body. Method according to one of claims 18 to 33, characterized in that the dressing is carried out from strip finished by a cold rolling operation.

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